Fringing + Canon L lenses

Hi to the forum, I'm new and found this forum thru a Rainer Viertlböck post. It's great to see the quality of info here.

I'm mostly a returning architectural/lifestle/garden photographer moving from film to digital. I started testing the D5 this past week with a 35mm F2 and was surprised to find so much fringing with chromatic aberration in high contrast areas of the image. I shoot in high contrast high flare situations a lot.

After searching out past posts on this forum, here is a partial quote by Asher on the subject.

"I stopped using the 50 1.4 for my digital work because of birefringence, purple blue lines between high contrast areas that bother me and Chuck Westfall of Canon USA says is a lens-sensor issue specific for each particular combination and there's nothing to change that. "

Does anyone know of a site or have some info on the Canon line of lenses and fringing? I noticed that the MTF curves for many of the regular EF lenses charted better then the L lenses at f8 and I usually shoot in the mid to high f stop range. But I haven't found comparative info on fringing.

How do the L lenses compare to the regular EF lenses on fringing at mid to higher apertures ? And how can I contact Chuck Westfall for their info to follow up on this?

To start my lens test ball rolling, I ordered the 20 f2.8, 24 f2.8, 28 f2.8, 35 f2.0 100 f2.8 macro and will keep them as backups if I think I need to get the L series lenses. I've held off on other lenses till I gather more info.

Any guidance will be greatly appreciated,

Allen Maertz

You might have a look here

You'll see that DPP does a pretty good

job processing a RAW file about it. I find it better than ACR and unfortunately this is an issue you'll face sooner or later pretty much with any lens. But selecting the best RAW processor can make a difference.
Of course shooting RAW will be almost mandatory for that.

Michael Fontana said:

You might have a look here

Click to expand...

Thanks Michael,

I see the 28mm schneider shift. My German is limited but I get the drift. I've previously owned both Nikon shift lenses which I've liked, but I'm trying to test out post processing digital solutions on the D5. Hence the CA questions. I also figure that I'll try out some stitching programs and see what I can get out of the Canon gear. Any suggestions? I used to use the Linholf Technikardan/Rollei MF/Nikon systems but I'm switching. I took a couple of years off while grappeling with the NYC Gallery system but now I'm back to make a living!


Allen

MArk Le said:

job processing a RAW file about it. I find it better than ACR and unfortunately this is an issue you'll face sooner or later pretty much with any lens. But selecting the best RAW processor can make a difference.
Of course shooting RAW will be almost mandatory for that.

Click to expand...

What is your top RAW converter pick for CA or overall?

Thanks,

A

ACR

but for critical work I do find DPP better for the colors. It reproduces colors for details (even small) where ACR won't.

for example I shot the wall of the studio where there are the portraits framed. DPP was able to reproduce the eyes of a model blue where on ACR they were more brownish. After that I did the same with a Nikon and again the Nikon software gave the same better colors on small details.

I had many problems with a shot of a tall building with the purple on top (where the building "touched" the blue sky). While on ACR the purple was evident, it was much better on DPP.

problem is that I need PS for all the rest... so I open with DPP and transfer to PS right away

MArk Le said:

but for critical work I do find DPP better for the colors. It reproduces colors for details (even small) where ACR won't.

for example I shot the wall of the studio where there are the portraits framed. DPP was able to reproduce the eyes of a model blue where on ACR they were more brownish. After that I did the same with a Nikon and again the Nikon software gave the same better colors on small details.

I had many problems with a shot of a tall building with the purple on top (where the building "touched" the blue sky). While on ACR the purple was evident, it was much better on DPP.

problem is that I need PS for all the rest... so I open with DPP and transfer to PS right away

Click to expand...

Are you using CS2 or CS3 for ACR? Do you think there is any difference.?

Thanks,

Allen

Allen Maertz said:

Are you using CS2 or CS3 for ACR? Do you think there is any difference.?

Thanks,

Allen

Click to expand...

Or rather, on CA fringing on the Canon lenses is the CS3 version any better then the CS2 version of ARC? I'm still basically looking for info on the L series lenses and the regular EF lenses with reguards to CA. Any info appreciated.

Greetings Allen,

As a general rule a "L" series lens will always our perform a non.

A few important thing is to know are:

• A "L" zoom will be as good as a non "L" prime at the same focal length.
  
• There are some lenses that are up to the "L" standard but are not labeled as such. (TSE 45 and 90)
  
• Manufacturing variations can invalidate most rules on a per lens basis.
  
• Even a perfect lens will show fringing with the right image pattern to pixel pitch spacing.

Will Thompson said:

Greetings Allen,

As a general rule a "L" series lens will always our perform a non.

A few important thing is to know are:

• A "L" zoom will be as good as a non "L" prime at the same focal length.
  
• There are some lenses that are up to the "L" standard but are not labeled as such. (TSE 45 and 90)
  
• Manufacturing variations can invalidate most rules on a per lens basis.
  
• Even a perfect lens will show fringing with the right image pattern to pixel pitch spacing.

Click to expand...

Thanks for the response Will,

I understand special case of pattern generation of CA fringing. I'll be using fixed lenses because I photograph in high contrast situations a lot. I noticed that the MTF charts on the L and the regular EF fixed lenses were quite comparable in general. I'm ususally f8 or higher in my shooting hence my motive to continuing to ask questions on general CA fringing on the Canon lenses.

Years ago I adapted my Zeiss SL66 lenses to replace the Mamiya 645 lenses because of flare using a modified Mamiya bellows rail. I was able to get all view movements, focus at infinity, electronic mirror up with electronic multiple flash, sharp bright pentaprism viewing and Zeiss lenses plus polaroids. I may be dusting off some of the old components and looking for a digital upgrade to that idea.

But, I'm still interested in anyone who has done any comparative testing of the Canon EF lenses in regards to CA fringing. Maybe most people have just gone to a software solution on this.

Thanks, Allen

Allen, Need a EOS bellows?

Hi Will,

I'll have to investigate the possibilities on the EOS bellows. But first I'll have to tech out the D5 and the simple existing lens solutions along with software and see what I can squeeze out of it.

Thanks, Allen

To answer my own question on CA, I found a site http://www.photozone.de/8Reviews/index.html#canon that charts CA in their lens tests. Thanks for all the other responses.

Allen

This is a subject worth revisiting. does one have a right to expect that L lenses will show essentially know obvious fringing or chromatic aberration wide open?

Asher

One suspect I have is the 50 1.2L!!

Asher Kelman said:

This is a subject worth revisiting. does one have a right to expect that L lenses will show essentially know obvious fringing or chromatic aberration wide open?

Click to expand...

Hi Asher,

It's hard to answer because there can be several causes for the fringing. It can be caused by overexposure, i.e charge leaking to neighboring sensels, it can be caused by Chromatic aberrations (Lateral and/or Longitudinal), and it can be caused by the Bayer CFA demosaicing of features that are insufficiently attenuated by the AA-filter (if such a filter is used).

The most recent incarnations of Lightroom (4.1), and Photoshop's ACR (7.1), have improved defringe tools when using the Process Version 2012 for Raw conversion. It is now possible to select the fringe color ranges that will be addressed and the strength of the correction. It is a global correction, but when it also reduces colors that are not fringes, then a local defringe with a minus 100 setting can be used to correct that. Here is a good explanation of the new tools.

Cheers,
Bart

Bart_van_der_Wolf said:

Hi Asher,

It's hard to answer because there can be several causes for the fringing. It can be caused by overexposure, i.e charge leaking to neighboring sensels, it can be caused by Chromatic aberrations (Lateral and/or Longitudinal), and it can be caused by the Bayer CFA demosaicing of features that are insufficiently attenuated by the AA-filter (if such a filter is used).

The most recent incarnations of Lightroom (4.1), and Photoshop's ACR (7.1), have improved defringe tools when using the Process Version 2012 for Raw conversion. It is now possible to select the fringe color ranges that will be addressed and the strength of the correction. It is a global correction, but when it also reduces colors that are not fringes, then a local defringe with a minus 100 setting can be used to correct that. Here is a good explanation of the new tools.

Cheers,
Bart

Click to expand...

Thanks for the reference.

Look at the edge of the woman's face. There's an extra line. Is that movement? I took the picture at ~ 1/400 sec at f 1.2






There's no color to the line. I just am puzzled. I also have pictures of a hook on a wall which suggest CA.



Asher

Asher Kelman said:

Does one have a right to expect that L lenses will show essentially no obvious fringing or chromatic aberration wide open?

Click to expand...

No, of course.

Especially the 50mm f/1.2. It is loaded with aberrations. So what? You are not photographing test charts or their design have changed a lot since the last time I used them.

The line on the face is her left cheek, unsharp from minimal depth of field. You would see colors (axial chromatic aberration) on a thin subject, not on a subject with this much axial extension.

Jerome Marot said:

No, of course.

Especially the 50mm f/1.2. It is loaded with aberrations. So what? You are not photographing test charts or their design have changed a lot since the last time I used them.

The line on the face is her left cheek, unsharp from minimal depth of field. You would see colors (axial chromatic aberration) on a thin subject, not on a subject with this much axial extension.

Click to expand...

Jerome,

I haven't come across example of the thick v. thin axial spread you refer to. do you have a reference or you just know. Presumably then, if you're correct, these lines might be abolished in the new Adobe Raw tools. I wonder if it's as developed in CS5 as I have that already.

Asher

I probably was not clear enough. Axial chromatic aberration refers to colors taken by objects out of focus. The typical example is a ruler photographed at an angle as in this image from photozone taken with the 50 f1.2:



It always happen, but it is particularly visible here because the "objects" are black markings and figures on a white background. If the ruler was entirely black or a dark color, you would not notice the color change, not because it would not be here, but because the human eye is less sensitive to subtle color changes in dark areas. That is what I intended to mean by "thin", but the word is poorly chosen.

Asher Kelman said:

Thanks for the reference.

Look at the edge of the woman's face. There's an extra line. Is that movement? I took the picture at ~ 1/400 sec at f 1.2

Click to expand...

Hi Asher,

No, it's not movement, but I suspect it might be "spurious resolution", or a certain bokeh effect. I don't know that lens well enough to be familiar with its rendering of OOF areas. Anyway, it's not what is commonly understood by (colored) fringing.

Cheers,
Bart

Bart_van_der_Wolf said:

Hi Asher,

No, it's not movement, but I suspect it might be "spurrious resolution", or a certain bokeh effect. I don't know that lens well enough to be familiar with its rendering of OOF areas. Anyway, it's not what is commonly understood by (colored) fringing.

Cheers,
Bart

Click to expand...

Interesting!

I'll ask Canon CPS. Do you think I can do any chart test that would allow one to know whether or not there's something wrong with the lens, or just its design characteristic?

Asher

Asher Kelman said:

Interesting!

I'll ask Canon CPS. Do you think I can do any chart test that would allow one to know whether or not there's something wrong with the lens, or just its design characteristic?

Click to expand...

You can do a deliberate front focus (and/or backfocus) shot of my test chart, and since it has a multitude of spatial frequencies and orientation angles, if there are design issues they will show up. For such OOF shots you can just use the image on your computer display, no formal printed version required since we're not testing for resolution.

For real lens problems (e.g. decentering), which I don't think are the cause, a well focused shot of a printed version of the chart will show if there is asymmetry in the central blur disk. But as said, my guess is that it is more a design oriented phenomenon, only correctable in post-processing or by avoiding certain backdrops.

Cheers,
Bart

Hi, Jerome,

Jerome Marot said:

I probably was not clear enough. Axial chromatic aberration refers to colors taken by objects out of focus.

Click to expand...

I think it would be more accurate to say that axial chromatic aberration means that the different wavelengths of an object focus at different planes, so that not all "components" could be in focus at the focal plane at the same time.

But of course a manifestation of that can be what you show with the ruler.

Best regards,

Doug

Hi Doug,

Well then, why is this not the same as simply stating that there's CA? What extra information does "axial" add??

Asher

Doug Kerr said:

Hi, Jerome,



I think it would be more accurate to say that axial chromatic aberration means that the different wavelengths of an object focus at different planes, so that not all "components" could be in focus at the focal plane at the same time.

But of course a manifestation of that can be what you show with the ruler.

Best regards,

Doug

Click to expand...

Asher Kelman said:

Well then, why is this not the same as simply stating that there's CA? What extra information does "axial" add??

Click to expand...

There are two types of chromatic aberration, axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, i.e. different points on the optical axis (focus shift). Transverse aberration occurs when different wavelengths are focused at different positions in the focal plane (because the magnification and/or distortion of the lens also varies with wavelength).

http://en.wikipedia.org/wiki/Chromatic_aberration

Hi, Jerome,

Jerome Marot said:

There are two types of chromatic aberration, axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, i.e. different points on the optical axis (focus shift). Transverse aberration occurs when different wavelengths are focused at different positions in the focal plane (because the magnification and/or distortion of the lens also varies with wavelength).

Click to expand...

Nicely said.

Asher,

It is the transverse chromatic aberration which is most often discussed here as an image impariment. It is the cause of "color fringes" that are offset radially (toward or way from the center) from the other wavelength components of the image, and (except when it result from some misalignment of lens elements) occurs for off-axis parts of the image

Best regards,

Doug

For illustration - here is an example of longitudinal CAs (lens used was Pentax F 135/2.8):



The Tamron 70-200/2.8 looks better (here at 122mm):


Best regards,
Michael

Michael Nagel said:

For illustration - here is an example of longitudinal CAs (lens used was Pentax F 135/2.8):

Farbenspiel​

Click to expand...

Hi Michael,

Yes, that's a typical (although severe) case of longitudinal CA, typically magenta in front of the focus plane, and green behind. Would be interesting to treat it with the new defringe tools.

Here's a Photoshop ACR 7.1 before/after defringing attempt on an Auto Focus Micro-Adjustment shot with my EF 135mm f/2 L, obviously used wide open:

Its front Longitudinal Chromatic Aberration is a very bright Red, and the rear LonCA is Cyan-Green. It is mostly gone by f/2.8 or f/3.5, but very obnoxious when one wants to exploit the very shallow DOF that a 135mm at f/2 can offer (also with a very nice bokeh). Now this has become a possiblity.

Cheers,
Bart

Bart,

highlights like from water reflections are almost a guarantee for longitudinal CAs when using the lens wide open (and often even stopped down).

There are only few lenses not showing this effect.

For me it was just curious, that a zoom lens with the same aperture proved to be less prone than a prime lens. The age of the prime lens may be an excuse.

Best regards,
Michael